Relationship DNA testing has helped police make a breakthrough in a high profile murder case more than 40 years after the crime was committed.

Karen Klaas, the ex-wife of Righteous Brothers star Bill Medley, was raped and strangled at her California home in 1976. Investigations into who killed the 32-year-old ran into a dead end but police now say they have identified her killer using DNA testing.

The cold case was first reopened in 2009 and investigators used evidence from the crime scene to put together a DNA profile of the person who attacked Karen. However, the profile did not match anyone in the United States’ DNA database so the team then turned to familial DNA testing.

This involves searching law enforcement database for people who could be biologically related to the suspect. It is a controversial method as some people believe it is an invasion of privacy for the family members.

Now the Los Angeles County Sheriff’s Department has identified Karen’s killer as Kenneth Eugene Troyer, a criminal who was shot dead after he escaped from a Californian prison in 1982.

Bill Medley told a press conference this week: “It’s just nice to close the book on this. I always had hope that I would find out.”

Matches identified suspect after 40 years

Detectives working on the case got two familial DNA matches when they searched databases for a third time last year. One of the partial matches had died while the other was convicted of a crime back in 2011.

They used this information to look into the family of the matches and discovered the link to Troyer, who had been wanted in connection to a number of sexual assaults, burglaries and armed robberies when he was killed.

Investigators then asked the Orange County coroner’s office for a sample of DNA and that matched the profile discovered at the crime scene. They also discovered he had been spotted walking in Karen’s neighbourhood a few days before her death.

Her son Darrin Medley told the Los Angeles Times: “I did not believe we could identify who committed this crime. Forty-one years later, we know what happened.”

Every person inherits half their DNA from their mother and half from their father. This means that biological relations will share DNA with each other.

This allows DNA testing to be used to work out whether two individuals are related to each other. AlphaBiolabs offers maternity and paternity testing which can identify whether someone is the mother or father of another person.

But we also carry out a wide range of other relationship DNA tests which can determine whether someone is related in another way.